Paleontologists use the position of fossilized bones to infer the environment in which animals perished. Many animal fossils appear in...
GMAT Critical Reasoning : (CR) Questions
Paleontologists use the position of fossilized bones to infer the environment in which animals perished. Many animal fossils appear in a head-thrown-back position called opisthotonos, a posture that veterinarians report being common in animals suffering from oxygen deprivation. This suggests that most of the animals whose bones are found in opisthotonos died from suffocation, probably trapped by a sudden mud slide or other deluge.
Which of the following, if true, most weakens the reasoning above?
Passage Analysis:
| Text from Passage | Analysis |
| Paleontologists use the position of fossilized bones to infer the environment in which animals perished. |
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| Many animal fossils appear in a head-thrown-back position called opisthotonos, a posture that veterinarians report being common in animals suffering from oxygen deprivation. |
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| This suggests that most of the animals whose bones are found in opisthotonos died from suffocation, probably trapped by a sudden mud slide or other deluge. |
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Argument Flow:
The argument moves from general scientific method (how paleontologists work) to specific evidence (fossil positions and vet observations) to a conclusion about cause of death. It's a classic evidence-to-conclusion flow that relies on comparing ancient fossils to modern animal behavior.
Main Conclusion:
Most animals found in the opisthotonos position died from suffocation, probably caused by sudden mudslides or floods.
Logical Structure:
The argument uses analogy and expert testimony. It takes modern veterinary knowledge about oxygen deprivation causing opisthotonos, applies it to ancient fossils showing the same position, and concludes the ancient animals died the same way. The logic depends on the assumption that the same body position indicates the same cause across time periods.
Prethinking:
Question type:
Weaken - We need to find information that would reduce our belief in the conclusion that most animals found in opisthotonos position died from suffocation due to mudslides or floods
Precision of Claims
The argument makes specific claims about: (1) most animals in opisthotonos died from suffocation, (2) they were probably trapped by sudden mudslides or floods, and (3) the opisthotonos position indicates oxygen deprivation based on modern veterinary observations
Strategy
To weaken this argument, we need to find alternative explanations for why fossils appear in opisthotonos position that don't involve suffocation from mudslides/floods. We can attack the link between the fossil position and the assumed cause of death, or show that opisthotonos happens for reasons other than oxygen deprivation, or demonstrate that the fossilization process itself could create this position
This choice actually strengthens rather than weakens the argument. If mudslides create conditions that promote fossilization and we find many fossils in opisthotonos position, this supports the conclusion that these animals were indeed trapped and suffocated in mudslides. The choice provides a mechanism that explains why we would find evidence of the proposed cause of death.
This choice also strengthens the argument by eliminating an alternative explanation. If geological shifts over time can't cause the opisthotonos appearance, then the position must reflect the actual death posture of the animals. This supports the argument's assumption that the fossil position accurately reflects how the animals died, making the suffocation conclusion more credible.
This choice significantly weakens the argument by providing an alternative medical explanation for opisthotonos that doesn't involve oxygen deprivation. If bacterial infections like meningitis can also cause this head-thrown-back position, then paleontologists can't automatically assume that fossils in opisthotonos died from suffocation. The animals might have died from disease rather than mudslides or floods, which directly undermines the main conclusion.
This choice strengthens the argument by providing additional supporting evidence. If fossils in opisthotonos are found in geological settings that show evidence of mudslides or deluges, this corroborates the argument's conclusion that these animals died from suffocation caused by such events. The geological evidence aligns with the proposed cause of death.
This choice supports rather than weakens the argument. If oxygen deprivation had the same physical effects on ancient animals as it does today, then the comparison between modern veterinary observations and fossil positions is valid. This strengthens the argument's foundation that ancient animals would have exhibited opisthotonos when suffocating, just like modern animals do.